Place 1 wonton wrapper on work surface. With pastry brush, brush egg white along edges; place 1 rounded tablespoon squash filling in center of wrapper, keeping filling away from edges. Top with second wrapper; press down firmly around filling to seal ravioli, pushing out any trapped air. Place ravioli on cookie sheet. Repeat with remaining filling and wrappers, using a second cookie sheet so that ravioli do not overlap. Let ravioli dry 30 minutes, turning over halfway through to evenly dry both sides.

Ten minutes before cooking ravioli, heat large saucepot of salted water to boiling on high. Add ravioli to pot; cook 3 to 5 minutes or until tender, stirring gently to separate ravioli.

Meanwhile, in 4-quart saucepan, cook butter on medium 3 to 4 minutes or until golden-brown, stirring. Remove from heat; stir in sage and 1/2 teaspoon each salt and freshly ground black pepper.

With large slotted spoon, lift out ravioli, 1 at a time; drain, still held in spoon, on paper towels. Transfer ravioli to saucepan with butter; gently stir to coat.